A massive people’s uprising is driving the opposition to President Trump. In Congress, the Congressional Progressive Caucus is an emerging center of that resistance.

This year marks the 25th anniversary of the CPC. Its first and founding director was an independent socialist from Vermont named Bernie Sanders. Now, co-chaired by Reps. Keith Ellison (D-Minn.) and Raúl M. Grijalva (D-Ariz.), the CPC is the largest Democratic House caucus, with 73 dues-paying members. Each election in recent years has provided it with dynamic new leaders — Wisconsin’s Mark Pocan, New York’s Yvette Clarke, Pennsylvania’s Matthew Cartwright, and now Washington’s Pramila Jayapal and Mayland’s Jamie B. Raskin.

Last weekend more than 30 of those members joined with activists from across the progressive landscape to share ideas and plot strategy at the annual summit of Progressive Congress. CPC members individually are already mobilizing against Trump. The challenge is whether the CPC can collectively begin to define the forward-looking agenda of the resistance.

After all, the CPC’s agenda has been vindicated again and again over the years. It was right to oppose the Iraq War, right to challenge ruinous corporate trade policies and catastrophic banking deregulation, and right to call for a bold green New Deal, with public investment driving economic recovery. Now, the CPC is right to demand progressive tax reform and higher taxes on the rich. It is right to call for Medicare for All and to push to expand, not cut, Social Security. It is right to join workers in championing a $15 minimum wage. It is right to urge an end to bloated defense budgets.

Getting it right, however, is small solace if you can’t get it done. The CPC has had some victories, usually in conjunction with outside movements. Most recently, its members — spearheaded by Rep. Rosa L. DeLauro (D-Conn.) — joined with a broad coalition of citizen groups to help defeat President Barack Obama’s Trans-Pacific Partnership before Trump ever took office. Too often, though, the CPC and its members have gotten it right but the Democrats have gone the other way.

To be sure, the CPC disappoints some activists on the left. The caucus hasn’t wielded the weight of its numbers (partly because it does not enforce unanimity among them) and is criticized for being reluctant to break with the Democratic leadership (not surprising since House Minority Leader Nancy Pelosi (Calif.) was one of the founders of the caucus). While its members are staunch on civil rights and social issues, they are more divided on bread-and-butter concerns. Strikingly, only the co-chairs — Ellison and Grijalva — plus two members — Rick Nolan (Minn.) and Peter Welch (Vt.) — stepped up to endorse Sanders in the Democratic primaries.

Increasingly, however, the CPC has the wind at its back. Occupy Wall Street, Black Lives Matter and Fight for $15 drove the debate. Sanders’s stunningly successful primary challenge galvanized the young around a bold agenda, showing its power. Hillary Clinton’s unexpected loss demonstrated the failure of the establishment.

And now, to paraphrase Mark Twain, Trump, like hanging, concentrates the mind. CPC members will help Democrats in rallying the resistance. They already know how to support outside movements and groups, and seed political organizing and education in their own districts and elsewhere.

More important, CPC members are ready to join together in championing a bold alternative to Trump, drawing from their own history and the Sanders platform. The Sanders candidacy demonstrated the potential. Now a range of citizen movements and grass-roots and activist networks are rallying around similar ideas, and others are recruiting and supporting candidates to run on this agenda.

That’s why Ellison’s candidacy to head the Democratic National Committee is so important. Ellison has pioneered grass-roots organizing and education in his own district. He has proved that principled progressives can win transformational victories. And he can help the party reconnect with working people. If he wins, the party will be able to capture more of the new energy.

Every year at the Progressive Congress summit, Minority Whip Steny H. Hoyer (D-Md.), No. 2 in the House Democratic leadership, hails the CPC, of which he is not a member, as “the soul of the Democratic caucus.” The sly put-down is implicit: You idealists cultivate our conscience, while we pragmatists get on with governing. Now Trump’s rise has exposed the catastrophic failures of the New Democrats, the Blue Dogs, the Wall Street wing of the party. It is time for the CPC to move from being the conscience of the Democratic caucus to its captain, from defining the alternative to defining the agenda. This won’t be easy. The CPC will have to raise its game and organize itself far more aggressively. Progressive senators such as Sanders and Elizabeth Warren (D-Mass.) have a bigger megaphone. But citizens on the march will find the leaders and members of the CPC standing with them.